class_docstr: 重载 StreamHandler 使得替换 sys.stdout 的时候能够生效。
docstr: Sets the StreamHandler's stream to the specified value,
  if it is different.
  
  Returns the old stream, if the stream was changed, or None
  if it wasn't.
docstr_tok: ["Sets","the","StreamHandler","'s","stream","to","the","specified","value",",","if","it","is","different",".","Returns","the","old","stream",",","if","the","stream","was","changed",",","or","None","if","it","was","n't","."]
code: def setStream(self, stream):
      """
      Sets the StreamHandler's stream to the specified value,
      if it is different.
  
      Returns the old stream, if the stream was changed, or None
      if it wasn't.
      """
      raise RuntimeError("Cannot set the stream of FStreamHandler.")
  
file_path: fastNLP/fastNLP/core/log/handler.py
imports: import logging
  import sys
  from logging import getLevelName
label_desc: Use image node_id 4 for calling the StdoutStreamHandler obj's underlying member method code with example usage: obj.setStream(stream) without return types